Bitcoin Forum
December 07, 2016, 06:24:09 PM *
News: To be able to use the next phase of the beta forum software, please ensure that your email address is correct/functional.
 
   Home   Help Search Donate Login Register  
Pages: « 1 2 [3]  All
  Print  
Author Topic: SHA-256 (fixed: maybe) hacked, man gets away with 7 blocks in 10 minutes  (Read 8385 times)
nathanrees19
Full Member
***
Offline Offline

Activity: 196



View Profile
June 22, 2011, 03:24:14 PM
 #41

I ran some quick numbers. If I'm correctly understanding the distribution, once the first block was found, the chance of finding the next 6 blocks in that time window was something like 0.0000002. However, this possibility has existed every time a block has been found. The chance of this streak happening at least once in 132000 or so blocks is greater than 99.7%. In fact, there is a very high chance that his has happened more than once. If I find the time, I could do an analysis of the whole block chain to see if this has happened before.

Is there an easy way to extract block timestamps from the chain?
If you evaluated the cdf of a gamma distribution with parameters 7 and 1/10min at 10min to get 0.0000002, and 1 - the pdf of the binomial distribution with parameters 132000 and 0.0000002 evaluated at 0 to get 99.7%, then I think it's correct.  I'm too lazy to calculate it, though.

Also, http://www.xkcd.com/882/

My knowledge of statistics is a bit rusty, so I decided to look at the actual blocks. I ran a script to evaluate, from each block, how many blocks were found less than 420 seconds beforehand.

The record was twelve.

There were 358 cases of 6 or more (ie. 7 blocks in under 7 minutes). If we only look at recent blocks (>100000), we still get nine cases of this happening.
1481135049
Hero Member
*
Offline Offline

Posts: 1481135049

View Profile Personal Message (Offline)

Ignore
1481135049
Reply with quote  #2

1481135049
Report to moderator
1481135049
Hero Member
*
Offline Offline

Posts: 1481135049

View Profile Personal Message (Offline)

Ignore
1481135049
Reply with quote  #2

1481135049
Report to moderator
1481135049
Hero Member
*
Offline Offline

Posts: 1481135049

View Profile Personal Message (Offline)

Ignore
1481135049
Reply with quote  #2

1481135049
Report to moderator
Advertised sites are not endorsed by the Bitcoin Forum. They may be unsafe, untrustworthy, or illegal in your jurisdiction. Advertise here.
snowboard789
Sr. Member
****
Offline Offline

Activity: 320


View Profile
June 22, 2011, 05:13:44 PM
 #42

why do people keep commenting on imperis posts? arent you the same guy proposed that bitcoin will have a negative value in usd?
just void the post.
Pages: « 1 2 [3]  All
  Print  
 
Jump to:  

Sponsored by , a Bitcoin-accepting VPN.
Powered by MySQL Powered by PHP Powered by SMF 1.1.19 | SMF © 2006-2009, Simple Machines Valid XHTML 1.0! Valid CSS!